Hydraulic coupling



Oct 15, 1946. w, rr s 2,409,255

HYDRAULIC COUPLING I Original Filed March 6, 1942 2 Sheets-Sheet 2 ATTORN S Patented Oct. 15, 1946 HYDRAULIC COUPLING Wilbur J. Crites, deceased, late of Bartlesville, Okla, by First National Bank in Bartlesville, executor, Bartlesville, Okla, said Crites assignor to Phillips Petroleum Company, a corporation of Delaware Original application March 6, 1942, Serial No.

Divided and this application February 1, 1944, Serial No. 520,898

1 Claim. 1

This invention relates to improvements in pumping machinery used in the production of oil from wells, and particularly to apparatus for hydraulically connecting a prime mover to a pumping device.

The present application is a division of copending application, Serial No. 433,676, filed March 6, 1942, issued as Patent No. 2,358,058.

In the pumping of wells by sucker rods, it is now common practice to operate the rods with an oscillating beam to which at one end is attached the sucker rods and at the other end a pitman which is actuated by a crank. To offset the weight of the rods and to store the energy incident to the dropping thereof, a counter-balance is used. The counter-weight is in a definitely fixed position approximately in a relative cyclic position of 180 from the load. On account of the elasticity of the sucker rods and tubing, the compressibility of the fiuid being produced and the ever changing stress throughout the pumping cycle, the counter-balancing effect should be ever changing both with reference to position and force applied to conform with both the stress requirements of the load and the regenerative effect of the falling sucker rods.

In the pumping of oil from wells by the means discussed herein, there are two types of stresses developed, namely; static stresses, or those that result from suspended loads, and dynamic stresses, or those that result from the application or interruption of motion. The destructive effect of static stresses is negligible, but dynamic stresses are extremely destructive and are the source of almost all mechanical failures. The greatest dynamic stress in the pumping of oil wells occurs from the interruption of motion and is normally at that point that the fluid is started in motion on the up-stroke after the elasticity of the rods has been expended. The greater the acceleration at this point the greater the stress, because the entire load must be set in motion from a static state. Therefore, at this point it is important to have a minimum rate of acceleration. Normally, although the stresses are of greater magnitude on the up-stroke of the rods, those on the down-stroke may be more destructive. On the down-stroke, the rods are either in tension from their own suspended weight or if the rate of imparted motion exceeds the actual rate of gravitational acceleration, the rods will be in compression. Compression stresses in a sucker rod system are not, per se, destructive, but on account of the high ratio of longitudinal to cross sectional area and absence of an immediate supporting medium, the rods will enter a bending stress at such time as the resistance to downward travel at the plunger becomes greater than the gravitational efiect at that point to the extent that the rod column above will be distorted. Unlike the stresses of tension and compression, the bending stress from distortion is not distributed throughout the length of the rods, but will be concentrated in a few places. The points of bending stress concentration will be at those points that oifer the least resistance to bending and repeated bending at such points will soon result in fatigue failures. Such stress concentration may result in shortening the life of the rods from the superimposed weight of the rods alone, but when the rate of applied motion is greater than the rate of motion due to gravity, the stress is increased, resulting in much earlier failure of the rods.

Many patents have been issued, including my Patent No. 2,20%,725, which tend to reduce acceleration as the load increases. Most of these are known as shock absorbers, but in all of these in which there is a definite speed relationship between the prime-mover and the load, the reactive effects may often be as destructive as the direct efiects would have been without the application of the devices which do not control the accelereration. In order to obtain the maximum stress reduction, the speed of the load must be independent of the speed of the prime mover.

The solution of the problem lies in having a coupling device, which is responsive to torque changes and in which there is substantially no reactive effect, between the prime mover and the load. Although the normal hydraulic coupling would have distinct advantages in its application to a system of this kind, it is obvious that a coupling in which the slip characteristics are adjustable would have greater merit than one in which they are not. Further, a minimum slip on the down stroke of the sucker rods will result in storing maximum energy in the flywheel and that controlled slippage on the upstroke of the rods will effect a minimum, 'stress occurrence.

The instant invention employs a type of coupling for hydraulically connecting a prime mover to a pumping unit in a manner whereby full mechanical advantage is obtained from the energy of falling sucker rods and full control of the sucker rods is obtained during the pumping cycle. It is to be noted that the instant invention may be employed in an oil well pumping system, such as that shown and described in U. S. Patent No. 2,268,701.

The primary object of the instant invention is to provide an apparatus for hydraulically connecting a prime mover to a pumpingdevice.

Another object of this invention is to provide a hydraulic coupling for use with well pumping equipment which stores the energy of the falling sucker rods in a flywheel and then utilizes said stored energy to assist the prime mover during periods of peak loads.

A further object of this invention is to provide a hydraulic coupling apparatus in conjunction with well pumping equipment which will reduce stresses in the pumping equipment, particularly in the sucker rods.

Another object is to provide a well pumping apparatus which will require less power for opera tion than present-day conventional equipment.

These and additional objects and advantages will be apparent to persons killed in the art by reference to the following description and annexed drawings, wherein Figure 1 is a plan View of the pumping equipment which may be employed in the practice of the instant invention Figure 2 is an elevation view of the pumping equipment shown in Figure 1;

Figure 3 is an elevation view of my invention partly in cross-section, of the hydraulic coupling device employed in the system that is shown in Figures 1 and 2;

Figure 4 is a sectional view of the invention, partly in cross-section, taken along the line 4-4 of Figure 3.

Referring to the drawings and more particularly to Figures 1 and 2, there is denoted therein a prime mover, such as a high slip type alternating current electric motor, by reference numeral l0. Rotary motion developed by prime mover Ii) is transmitted by shaft H to a fly- Wheel I2 and to one portion of a positive displacement rotary pump which is adapted to serve as a coupling means l3 that is connected to the shaft. A pulley M, which is secured to another shaft |5 that is connected to another portion of coupling means I3, transmits power through V- belts I6 from the prime mover to a drive wheel I1 which is connected to one end of a pitman l8. The other end of the p t a s Conn c to one end of a walking beam I3 which is supported by a Samson post 23. The other end of the walking beam is connected to a sucker rod string 2| which is employed in lifting fluid from an underground formation. In the lifting of fluid, sucker rod string 2| reciprocates through conventional surface well equipment 22.

Turning neXt to Figures 3 and 4 for a description of coupling means l3, it is to be noted that there is employed a positive displacement rotary pump which is adapted to serve this purpose. It is not desired to limit the instant invention to any particular type of positive displacement rotary pump means, as other types may be employed successfully, but rather there is shown and hereinafter described this particular type for the purpose of disclosing the instantinvention. Shaft I5 is integral with a housing 23 or the coupling means, and is adapted to accommodate a pump rotor 24 which is integral with shaft ll. Housing 23 extends outwardly over shaft and is provided with a packing gland 25 which is employed to hermetically seal the housing and to prevent the leakage of a working fluid which is placed interior of the housing and utilized to operate the coupling means. In adapting the pump to ahydraulic coupling, there is provided housing 23 with an interior liner partition 23 in which rotor 24 is rotatably positioned. Partition 26 is adapted to form an inlet chamber 21 and a discharge chamber 28 which connect with a passage 29 that is formed in housing 23 through an inlet port 30 and a discharge port 3|, respectively. Housing 23 also contains an idler pin 32 which is attached thereto and which rotatably carries an idler gear 33 that meshes with rotor 24, and a fixed crescent-shaped member 34 that is positioned between the rotor and the idler gear.

In order to control the flow of working fluid through passage 29, there is formed a valve seat 35 in the passage. The valve seat receives a valve head 36 which is adapted to be slidably positioned on one end of a valve stem 37. The valve head is provided with an interior bore 38 which permits a desired lateral movement of the valve head along stem 31. A compression spring 39 of any desired strength is carried on the valve stem which extends beyond housing 23 and which is connected at its outer end to a thrust plate 40 that is rotatably positioned on shaft l5. One or more stop assemblies 4|, each having a compression spring 42, which is identical to spring 39, are attached to housing 23 and to the thrust plate, which is maintained perpendicular to the central axis of shaft l5 at all times. Thrust plate 40 is urged to the right by springs 39 and 42, and to the left by an adjustment collar 43 which in turn is moved to the left by a yoke 44 that is attached to the adjustment collar in a pivotable manner, and which carries a rack 45 on its upper end. A pinion 46, which meshes with the rack to move the adjustment collar, is mounted in a well known manner on a support 41 which also assists in supporting yoke 44. A thrustbearing 48 is preferably placed intermediate thrust plate 40 and adjustment collar 43 to facilitate relative movement therebetween.

In operation, the apparatus is assembled as shown in the drawings and the interior of housing 23 is filled with a desired working fluid. It is to be noted that during a complete cycle of operation of the coupling 3, as shaft rotates rotor 24 clockwise in Figure 4, the working fluid is discharged into chamber 28 from which it flows through port 3|, passage 29, port 30, and thence into chamber 21 from which it is pumped again into chamber 28. It is to be further noted that when valve 36 is seated that the coupling is hydraulically locked since no fluid can flow through passage 29, causing shafts II and I5 to rotate substantially at the same rate of speed. On the other hand, if valve head 36 is open, the rotation of shaft |5 will be a function of the pressure of the fluidpumped from port 30 to port 3|, whereby the fluid acts upon rotor 24. Some intermediate position for valve 36 will usually effect the mostdesired rate of rotation of shaft I5. With a varyingload, such as that of sucker rods 2|, the rotational speed of the shaft will further vary with variations in the torque of shaft l5 which varies with the load of the sucker rods. Let us assume that the prime mover has been placed in operation, that valve 35 is placed in a desired spacedrelationship with valve seat 35, and that the umping equipment shown in Figure 1 is set into operation with sucker rods 2| just beginning to move upwardly. At this point in the pumping cycle, the load on sucker rods 22 is at substantially a minimum. But as the rods move upward they are elongated without any appreciable movement of the plunger but with increasingrod load which increases the torque of shaft I5 and causes the shaft to slow down. Due to the amount of fluid passing valve 35, when shaft I5 is slowed down, the acceleration of the rods occurs gradually Without subjecting the equipment to severe stresses. As the rods begin to pick up speed, the torque on shaft [5 decreases, less fluid passes valve 36, and shaft rotates more rapidly. As the rods reach the end of the upward stroke and start downwardly, the weight of the falling rods accelerates shaft l5 until it rotates at a faster rate than shaft I I, causing the working fluid in coupling l3 to be pumped in a reverse direction from chamber 2'! to chamber 28 through passage 29 where the fluid acting against the partially opened valve head 36 causes it to move over stem 37 and seat upon valve seat 35, closing passage 29 and hydraulically locking my device. Thus, the energy of the falling rods is transmitted through shaft I5, coupling I3, and shaft H to flywheel I2 where the energy is stored in the rotating flywheel. Not only does the flywheel decrease the speed of the falling rods, but also at the end of the downward stroke and at the beginning of the upward stroke, the energy stored in the flywheel is utilized in assisting the prime mover to accelerate the rods upwardly. When the rods complete their downward movement, flywheel I 2 causes shaft H to rotate more rapidly than shaft l5, causing the working fluid to be pumped through passage 29 in the normal direction, opening valve 36, whereupon the rods are accelerated upon gradually in accordance to the torque in shaft I5.

It is to be understood that although there is described the application of the device to pumping equipment, that it may be adapted to operate many other types of machinery and employed therewith advantageously.

From the foregoing, it is believed that the apparatus for practicing the instant invention will be readily comprehended by persons skilled in the art. It is to be clearly understood, however, that various changes in the apparatus herewith shown and described and in the modes of operation outlined above may be resorted to without departing from the spirit of the invention, as defined by the appended claim.

What is claimed is:

A fluid coupling for transmitting energy from a rotatable driving shaft to a rotatable driven shaft comprising a housing adapted to be connected to one of the above mentioned shafts; a positive displacement pump including a pump chamber formed within the housing, a pump rotor rotatably disposed in the chamber and adapted to be connected to the other above mentioned shaft, a fluid inlet and a fluid outlet communicating with the chamber; a conduit establishing communication between the inlet and the outlet; and valve means for controlling the flow of fluid through the conduit, comprising a valve seat in the conduit, a valve stem, a valve head slidable on the stem to seat on the valve seat, yieldable resilient means urging the stem away from the seat, an annular plate secured to the stem and disposed around the adjacent one of the shafts, and means slidable anct rotatable relative to the last mentioned shaft to adjust-the stem toward the seat by overcoming the force of the yieldable means.

WILBUR J. CRITES, FIRST NATIONAL BANK IN BARTLESVIILE, By WALTER E. DANNEBURG,

Trust Ojficer,

Administrator of the Estate of Wilbur J. C'rites,

Deceased. 

